What condition results from a deficiency of iron?

Iron-deficiency anemia is the condition that results when the body lacks enough iron to produce normal amounts of hemoglobin. Because hemoglobin carries oxygen inside red blood cells, the deficiency can reduce oxygen delivery to tissues and cause fatigue, weakness, shortness of breath, dizziness, or reduced exercise capacity.

Iron deficiency often develops in stages. The body first uses stored iron, commonly measured through ferritin, while blood hemoglobin may remain normal. If the shortage continues, red blood cells become smaller and contain less hemoglobin, producing the pattern called microcytic, hypochromic anemia. Blood loss, insufficient dietary intake, poor intestinal absorption, pregnancy, and increased growth demands are common causes.

The condition is not the same as thalassemia, a usually inherited disorder of globin production, or pernicious anemia, which involves vitamin B12 absorption. Treatment generally requires finding and addressing the cause as well as replacing iron through diet, oral supplements, or intravenous therapy when appropriate. In adults, unexplained iron-deficiency anemia can signal hidden gastrointestinal bleeding and warrants medical evaluation.